Too far, unless you get the ferry from there back, so a one way bike ride and a booze cruise back. The top end is all lovely but you will be spoilt for that in south France. I would go west coast France. Touch Andorra, Along the med to Monaco, missing out Marseilles, touch Italy, through the alps, touch Switzerland or Luxembourg (or both - but they are boring places), into Belgium for some cheap fags and then home. 9 days sounds about right.